A fuel is a substance which is used as a source of energy and produces heat as a result of combustion.
1.1) FOSSIL FUELS
The fossil fuels are formed by the anaerobic decomposition of dead organisms. The decomposition of buried organisms & their resulting fossil fuels take millions of years and sometimes this time period exceeds 650 million years. The fossil fuel such as coal, petroleum, and natural gas consists of high percentage of carbon. Fossil fuels contain volatile compounds and methane has low carbon hydrogen ratios.
It takes millions of years to form non-renewable sources of energy and reserves are depleting at a very faster rate than its formation rate. Usage and production are major concerns for the environment. Alternatively, focus on the development of renewable sources is done tomeet the increased demand.
1.2) NON FOSSIL FUELS
Non fossil fuels are the renewable sources of energy (nuclear energy, wind energy, solar energy, water generated energy etc.). They do not depend on burning up limited supplies of coal, oil, or natural gas but provide means of generating power that can be utilized indefinitely.
Since non fossil fuels are renewable sources of energy that can be tapped for millions of years and they will not get finished, therefore, they are considered extremely important for our future generation. These fuels are environment friendly as they produce much less pollution as compared non-renewable sources of energy. Governments of many countries are focusing on the usage of renewable sources of energy so as to reduce pollution produced by their countries.
The disadvantage of using fossil fuel is that it results in increased pollution. When fossil fuels such as coal, petroleum & natural gas are burned to produce energy, they release carbon dioxide (CO2). This excess amount of CO2 increases pollution and results in greenhouse effect whereas; non fossil fuels do not suffer from this disadvantage.
The search for more environment friendly and renewable sources of energy is going on so as to reduce pollution caused by non-renewable sources of energy and to maintain ecological balance. The government has made lot of efforts so as to reduce the dependency on non- renewable sources of energy such as petroleum fuels for power generation and transportation all over the world.
1.3) DIESEL ETHANOL BLEND
Diesel engines are used as a source of power in medium and heavy-duty applications because they result in lower consumption of fuel and emissions of unburnt hydrocarbons and carbon monoxide are less as compared to petrol engines. When supply of petroleum fuel was expensive or difficult to obtain, vegetable oil was used as a fuel in diesel engines and it resulted in successful running of engine. Later on when there was ease of supply of petroleum products, the replacement of vegetable oil was done with diesel. Therefore, the dependency on vegetable oil was reduced to a great extent and the researches were intended for the improvement of diesel fuel. Due to high heat efficiency and low emissions, diesel engines have received attention. The strict emission standard and inadequate petroleum reserves, alternative fuels for CI engine have been used. Ethanol is a prospective fuel for vehicle, as it is a renewable fuel and contains oxygen which can be blended with diesel or it can be directly injected into the cylinder. Ethanol, C2H5OH, (also called Ethyl Alcohol) is a clear colorless liquid and it has a pleasant smell and it is the second member of the aliphatic alcohol series.
Many studies have been conducted on the usage of ethanol in diesel engines, they focusses on these three aspects:
1. Appliance techniques of ethanol on diesel engine
2. Fuel properties of ethanol-diesel blends.
3. Ethanol-Diesel blends combustion and emission characteristics.
Solubility of ethanol in diesel is affected by the temperature and water content as ethanol is a polar molecule and moreover high proportion of ethanol to diesel is difficult, particularly under low temperatures. An emulsifier or co-solvent should be added to mix ethanol- diesel blend. The substance which stabilizes an emulsion (mixture of two immiscible liquids) by increasing its kinetic stability is known as emulsifier(also known as emulgent). The important factors of blend with ethanol are that it forms aromatic hydrocarbon compounds; it is a middle distillate and content of wax in diesel. The emulsifier used for our project is ENER diesel.
The appliance techniques of ethanol on diesel engine are divided into the following three classes:
(1) High pressure pump is used to blend ethanol-diesel.
(2) Carburetion or manifold injection is used for the fumigation of ethanol to the intake air charge. Ethanol amount is limited because there is starting of engine knock at high loads, and to prevent flame quenching and backfire at low loads.
(3) An extra high-pressure injection system and major design change of the cylinder head are required in dual injection system.
(4) An emulsifier or co-solvent is used to mix the two fuels (diesel and ethanol) to prevent their separation and no technical modifications are required on the engine side.
The physicochemical properties of ethanol-diesel blends such as surface tension, density of fuel, viscosity of fuel, specific heat of fuel, calorific value and cetane number of fuel plays a very important role as they have great effect on injection of fuel, atomization of fuel mixture to water droplets, ignition and combustion characteristics of fuel, as well as cold-start problem, power, consumed by the fuel and emission characteristics of engine. More, if there is leakage problem in conventional tank, alternatives such as fuel pipe and sealing part can be provided. Since the flash point of ethanol is low, the focus is done on the transportation, storage and usage of fuel. The cetane number which is defined as the percentage, by volume of normal cetane in a mixture of normal cetane and α- methyl naphthalene is an important fuel property for diesel engines. It determines the knock resistance property of diesel engine and also influences engine start-ability characteristics, emissions, and peak cylinder pressure.
For lab testing, there are 2 diesel engines of same specifications. These engines are fuelled with E10 and diesel. Each engine is run for 512 hours. After completion of every eight cycles, readings are taken. The performance characteristics and emissions are measured.
2.) LITERATURE REVIEW
2.1) 'Performance And Emission Characteristics Of Diesel Engine Fueled With Ethanol-Diesel Blends In Different Altitude Regions' By Faculty Of Transportation Engineering, Kunming University Of Science And Technology, Kunming (650224, China).
The comparative experiments of turbocharged diesel engine fuelled with diesel and its blends with ethanol( E10, E 15, E20 and E30) were carried out under different atmospheric pressures (81kPa, 90kPa and 100kPa) so as to study the performance & emission characteristics. The experimental results showed that the brake-specific fuel consumption (BSFC) of ethanol-diesel blends gets improved as the atmospheric pressure is increased. It was observed that at 81kPa, HC and CO emissions for blends were increased with increase in engine speed and load whereas, at 90kPa and 100kPa, the effects of engine speed and loads and amount of ethanol on HC and CO emissions are slightest. NOx emissions are unaffected by the increase in pressure and increase in amount of ethanol. When the atmospheric pressure is below 90kPa, the soot emissions of ethanol diesel blend is greatly reduced. If the atmospheric pressure is above 90kPa, the influence weakens. Smoke emissions are decreased as the amount of ethanol in blends is increased.
2.2) 'The performance and emission characteristics of unmodified diesel engines fuelled with ethanol- diesel blends' By J. I. Dominguez, E. Miguel CIDAUT, Parque Tecnológico De Boecillo, Parcela 209, ES-47151 Boecillo, Valladolid, Spain R. Arjona, C. Millán Abengoa Bioenergía, Av. Buhaira 2, ES-41018 Seville, Spain.
The comparative experiments were carried out with the use of new as well as waste oil as source for biodiesel fuel for compression ignition engine. The study of performance and emission characteristics was carried out for ethanol diesel blends and diesel and comparisons were made for blends with that of pure diesel. The results showed that the calorific value was reduced to about 13.43% for waste oil biodiesel and 7.24% for unused oil biodiesel. Also, there was increase in density of fuel when comparison was made with pure reference fuel. When the performance characteristics were measured, there was increase in power, brake thermal efficiency and torque and there was decrease in the specific fuel consumption. This was achieved for both low and high loads.
2.3) 'The performance and emission characteristics Of Diesel Engine fuelled with diesel and Blends Of Karanja Methyl Ester (Biodiesel) by H Raheman* And A G Phadatare Assistant Professor And Graduate Student, Agricultural And Food Engineering department, Indian Institute Of Technology, Kharagpur 721302, India.
This paper showed the comparative study of the properties of (KME) and its blend with diesel (20 to 80% by volume) and diesel in a diesel engine. The performance parameters such as torque, brake power, brake specific fuel consumption, exhaust gas temperature and brake thermal efficiency were measured as well as CO, HC, NOx emissions and smoke was measured so that the behaviour of diesel engine can be evaluated and computed for the above mentioned fuels. The results showed that there was decrease in emissions and performance parameters were improved. So karanja esterified oil can be used as an appropriate alternative fuel for diesel and can help to reduce pollution.
2.4) The study of safety and performance characteristic of Ethanol/diesel blends by L.R. Waterland, S. Venkatesh, and S. Unnasch TIAX LLC Cupertino, California.
To reduce the dependency on non renewable sources of energy such as petroleum and to reduce emissions, ethanol diesel blends can be used in heavy duty vehicles. The preparation of stable ethanol diesel blends(E10 & E15) is done by the method of splash blending. The ethanol- diesel blend cannot be sold legally in most of the states as it does not meet all the ASTM standards for diesel fuels. Ethanol diesel blends have good flammability characteristics. In enclosed spaces such as fuel storage and tanks ethanol concentrations are flammable over temperature range of 13 to 42°C, typical ambient temperatures. There are increased chances for fire and explosion hazards for E-diesel blends as compared to diesel fuel. The other deficiencies include decreased maximum power, the chances of fuel pump vapour lock are increased, and life of fuel pump and fuel injector is decreased as lubricate of ethanol is less. The safety and performance risks of Ethanol- diesel blend are also evaluated and compared with that of diesel. The safety risks which were identified were risks of fire. The most considerable safety risks identified related with the explosion or fire was the storage of fuel in fuel tanks, and the leakage of fuel resulting from traffic accidents of tankers and fleet vehicles. However, the safety risks can be reduced if the infrastructure and vehicle modifications are employed in the methanol fuelled heavy-duty vehicle demonstration programs that were performed in the 1980s and early 1990s. The following actions can be performed so as to reduce safety risks:
• The fuel storage tank vents and the vehicle tank vent and fill openings must be designed so that they are fit for use with ethanol
• All fuel transfer processes including vehicle fuelling must include effective vapour recovery systems.
• Electrical ground connection between the vehicle and the fuelling station must be properly established.
• Vehicle fuel tank level detectors of an essentially safe design must be incorporated.
2.4) NEED OF THE PROJECT
These days environmental pollution is increasing day by day because of fossil fuels such as petroleum products and these fuels are non- renewable sources of energy. Therefore, government is taking steps towards the search of more environmental friendly and non- fossil fuels. Ethanol is a renewable source of energy obtained from sugarcane, molasses etc. Thus, to reduce the dependence on fuel imports and non- renewable sources of energy, this test is performed.
This test will also help us to find the performance characteristics of diesel engine, effect on emissions.
3. OBJECTIVES
3.1) Evaluation of physicochemical properties of diesel ethanol and their blends.
In this we have measured the following properties :-
Viscosity - It is measure of internal resistance to a fluid which is being deformed either by shear stress or tensile stress. It is the fluid's internal resistance to flow.
Density - It is defined as mass per unit volume.
Calorific Value - The quantity of heat required to raise the temperature of 1 gm of substance by 1 deg C.
Surface Tension - It is the property of surface of liquid that allows it to resist an external force.
Cloud Point - It is the temperature at which cloud or haze of crystals appear at the bottom of the test jar, when the sample is cooled under prescribed conditions.
Flash Point - It is the lowest temperature at which vapour above a liquid will ignite when exposed to the flame. It is the measure of both volatility and flammability.
Pour Point - It is the lowest temperature expressed in multiples of 3â-¦C at which the oil is observed to flow when cooled and examined under prescribed conditions.
Fire Point - It is the temperature at which fuel will continue to burn for at least 5 seconds after ignition by an open flame. In general fire points can be assumed to be about 10% higher than the flash points.
3.2) Performance and emission analysis by using diesel and E10 as test fuel
In this we have measured the following performance parameters:-
Brake specific fuel consumption, Brake thermal efficiency, Exhaust gas temperature.
We have also measured the following emissions:-
The CI engine exhaust gases contain oxides of nitrogen (NOx), Carbon dioxide(CO2), Carbon monoxide (CO) and organic compounds which are unburned or partially burned Hydrocarbons (HC).
4. METHODOLOGY PROPOSED
4.1) PREPARATION OF TEST FUELS
The fuels used are diesel and E10.
E10 is prepared by mixing 10% ethanol to diesel and the amount of emulsifier (a substance which stabilizes an emulsion) added is 1.4%.
4.2) PHYSICOCHEMICAL PROPERTIES OF ETHANOL AND DIESEL
By this test, the properties which we are going to measure are:
4.2.1) VISCOSITY
Viscosity is also defined as fluid friction.
It can be measured by an instrument called as viscometer. Viscosity can be measured under one flow condition only. There are two conditions for measuring viscosity either the fluid remains stationary and an object moves through it, or the object remains stationary and the fluid moves through it.
The viscometer available in lab is Rotational Digital Viscometer. The specifications of viscometer are given below:
Setup no.: SERIAL- EXPL300009, CODE: V300003- Fungilab made
MODEL: FUNGILAB (EXPERT- L SERIES)
Digital direct reading viscometer( As per ASTM/ BIS) with-
Graphic Display (Resolution with low viscosity adapter: For lower than 10 cp: 1, for above 10 cp: 1)
Repeatability: 0.2%, Touch key controls with 6 key, auto test with sound and visual alarm, viscosity reading in cP, mPa.
Sensitivity: 1cP
Accuracy or precision: +/- 1% of full scale
Unit convertor - SI to CGS.
Kinematic viscosity ( centistrokes/strokes) (Ranges: 1 to 100cSt)
Temperature margins: 0 to 100deg C with +/-0.1 deg C precision)
Instruments internal memory more than 10,000 data
Power requirement: 220-240 and 50/60 Hz frequency
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Figure 4.2.1 Viscometer
4.2.2) DENSITY
The mass density or density of a material is defined as its mass per unit volume. The density of a material varies with temperature and pressure. (The variance is typically small for solids and liquids and much greater for gases.) Increasing the pressure on an object decreases the volume of the object and therefore increases its density. Increasing the temperature of a substance decreases its density by increasing the volume of that substance.
Density of diesel fuel oil at 15 °C is 820 - 950 kg/cum.
Density of Ethanol is 789 kg/cum at 20 °C.
The instrument used to measure the specific gravity (relative density) of the fluid is called Hydrometer. Relative density is ratio of the density of the liquid to the density of water. It consists of a cylindrical stem which is made of glass and a bulb weighted with mercury or lead shot to make it float upright. To measure the viscosity, pour the liquid into a tall container, often a graduated cylinder, and the hydrometer is gently lowered into the liquid until it floats freely. Note down the point at which the surface of the liquid touches the stem of the hydrometer. There is a scale inside the stem to take the reading. There are a variety of scales and they are used according to the requirement.
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Figure4.2.2- Hydrometer
4.2.3) CALORIFIC VALUE
The calorific value is an essential feature for each substance. Its unit is Kcal/kg or KJ/kg. Bomb calorimeter is an instrument which is used to measure the calorific value of fuel. It provides a simple, inexpensive yet accurate method for determination of heat of combustion. The calorimeter used for measuring the heat of combustion of a particular reaction is of constant volume type. When a particular reaction is carried out bomb calorimeters have to withstand high pressure within the calorimeter so as to measure the reaction. The energy used for igniting the fuel is electrical energy; as the burning of fuel is taking place the surrounding air will get heated up; the air expands and moves out of calorimeter through a tube.
Principle:
A sample is weighted and placed in a heavy- duty stainless steel cylinder called as 'bomb'. The bomb is then sealed with oxygen and the sample is ignited electrically. The complete oxidation of the compound releases heat and this is measured through the temperature change of the water bath surrounding the bomb. A digital sensor measures the rise in temperature. The heat of combustion at constant volume can be calculated from the resulting rise in temperature. We will take an ignition wire of 6 cm and a thread of 10 cm.
The following formula is used to measure the calorific value of diesel and E10:
W= HÃ-M+(CVt+CVw) / T
Where,
W= water equivalent in calories per degree centigrade
H= known calorific value of benzoic acid in cal/ gm=6319 cal/gm
M= mass of sample in grams
CVt = calorific value of thread= 2.1/cm (when using thread of 10 cm, CV of thread= 21 cal)
CVw= calorific value of ignition wire= 2.33/cm (when using wire of 6 cm, CV of wire= 9.32 cal)
T= Final rise in temperature in deg C
Formula for calorific value of sample:
CVs= TÃ-W- ( CVt+ CVw)/ M
Where, CVs= calorific value of sample
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Figure 4.2.3- Bomb Calorimeter
4.2.4) SURFACE TENSION
This property is caused by cohesion of like molecules, and is responsible for many of the behaviors of liquids.
The instrument used for measuring surface tension is called ultrasonic interferometer. It is used for the measurement of ultrasonic velocity in liquids with high degree of accuracy. The name of the equipment is: Multifrequency Ultrasonic Interferometer Model M-81 S.
Principle:
The principle used in the measurement of velocity (v) is based on the accurate determination of the wavelength(λ) in the medium. Ultrasonic waves of known frequency (f) are produced by a quartz crystal fixed at the bottom of the cell. These waves are reflected by a moveable metallic plate kept parallel to the quartz crystal. If the separation between these two plates is exactly a whole multiple of the sound wavelength , standing waves are formed in the medium. This acoustic resonance gives rise to an electrical reaction on the generator driving the quartz crystal and the anode current of the generator becomes a maximum.
If the distance is now increased or decreased and the variation is exactly one half wavelength (λ/2) or multiple of it, anode current becomes maximum. From the knowledge of wavelength, the velocity(v) can be obtained by the relation:
Velocity= wavelengthÃ- frequency
v = λÃ-f
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Figure4.2.4- Ultrasonic Interferometer
4.2.5) EXHAUST GASES
Exhaust gases consist of oxides of nitrogen, carbon monoxide, unburnt hydrocarbons, particulate matter & smoke. An instrument used for measuring exhaust gases is gas analyzer.
The composition of exhaust gas was measured using exhaust gas analyzer( AVL DIGAS - 4000 model).The emissions measured by it are: NOx, CO2, CO,HC and O2.It uses the principle of non- diffractive infrared radiation (NDIR) and for measurement of O2 electrochemical method is used.
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Figure4.2..5- Gas Analyzer
4.2.6) SMOKE
It is a visible indicator of combustion process and results due to incomplete combustion. The instrument used for measuring smoke is smoke meter.
For measuring the opacity of exhaust gas, smoke meter(AVL Austria,437) was used. The extinction of light between the light source and receiver in a pipe filled with exhaust gases is defined as the exhaust opacity. The purpose of measuring smoke opacity is that it quantifies the amount of particulate matter present in the engine exhaust. Smoke meter consists of a chamber provided with non- reflective inner surfaces and exhaust gases are made to pass through it. The light is made to pass through this chamber. The source of light is incandescent bulb having a temperature range of 2800K to 3250K. The light is made to passed through the chamber and made to fall on a photocell placed at the other end of the chamber. The current a photocell delivers varies linearly to the intensity received by it. When the light is made to pass through the chamber with exhaust smoke, the particulate matters that are present in the smoke, obstructs the path of light. Thus only a fraction of light is reached through the photoelectric cell and a voltage signal is generated. The voltage signal is the inverse of the opacity of exhaust gases.
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Figure4.2.6- Smoke Meter
4.2.7) CLOUD POINT AND POUR POINT:
The pour point and cloud point are measured by using cloud point and pour point apparatus.The cloud point and pour point are related to the flow conditions of crude and its products at low temperature.
The cloud point gives the rough idea of the temperature above which the oil can be handled safely, without any fear of congealing or filter clogging.
The pour point is determined to estimate the temperature at which a sample of oil becomes sufficiently solid to prevent its movement by pumping.
The pour point temperature depends to a large extent on the thermal history of the sample. The pour point also indicates the waxy nature of the sample.
Principle:
After preliminary heating, the sample is cooled at a specified rate and examined periodically ( in this, examined at intervals of 3 deg C for flow characteristic). The temperature at which a cloud is first observed at the bottom of the test jar is recorded as the cloud point and the lowest temperature at which oil ceases to flow is recorded as pour point.
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Cloud Point and Pour Point Apparatus
4.2.9) FLASH POINT AND FIRE POINT
The flash point and fire point are measured by flash point and fire point apparatus (Pensky- Martens Apparatus)
Principle:
Flash point is taken as the temperature when a flash first appears at any point on the surface of the material in the cap, continue the process of heating, when the oil ignites and continues to burn for a period of at least 5 seconds, this temperature is recorded as fire point.
Penskey- Martens Apparatus
4.3) SCHEMATIC DIAGRAM OF ENGINE TEST RIG
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Figure 4.3- Schematic Diagram of Engine Test Rig
5.6 Experimental set up for engine testing
5.6.1) Engine :
A suitable arrangement is provided for two engines which permit wide variation in controlling parameters. An experimental set up is shown in figure 2.Kirloskar Pvt. Ltd. has manufactured these engines. This is a single cylinder, four stroke, vertical and direct injection naturally aspirated engine. In order to cool the engine water cooled cooling system is provided. Gravity fuel feed system is provided for the fuel supply which contains efficient paper element filter. In this fuel tank is placed at higher level than the engine and by its own weight fuel flows from the tank to the carburetion injection pump. Main and large end bearings and camshaft bush are provided with the force feed lubrication system in which pump forces oil into the engine bearings.
The specification of the engine in detail is given below
Engine specification for the proposed study:
Model : AVI (Kirloskar Make)
Number of cylinders
One
Bore X Stroke
80 x 110 mm
Cubic Capacity
0.553 lit
Compression Ratio
16.5:1
Rated Output as per BS5514/ISO 3046/IS 10001
3.7 KW at 1500 rpm
SFC at rated hp/1500 rpm
245 g/KWh (180 g/bhp-hr)
Lubrication Oil Consumption
1.0% of SFC maximum
Lubrication Oil Sump Capacity
3.3 lit.
Fuel Tank Capacity
6.5 lit
Fuel Tank re-filling time period
Every 6 hours engine running at rated output
Engine Weight(dry) without flywheel
114 Kg
Weight of flywheel
33 kg- Standard
Rotation while looking at the flywheel
Clockwise
Optional - Anticlockwise
Power Take-off
Flywheel end
Starting
Hand start with cranking handle
Table 1 : Specification of Kirloskar make single cylinder direct injection diesel engine
Fuels to be Selected -
Diesel
Ethanol (Diesel with 10% neat Ethanol)
Experimental Set - up: It consists of test engine which is coupled to electric shunt load along with controller. For measuring the fuel volumetric fuel consumption unit is provided. A surge tank is connected to an orifice meter through which air is supplied to the engine. For measuring the temperature of air entering and leaving the fuel filter, lubrication temperature, temperature of exhaust gas and coolant water, thermocouple is used. To measure the emissions of the engine (CO, CO2, NOx, UBHC) an exhaust gas analyzer is used. A smoke meter is used to measure the smoke emissions of the engine.
5.6.2) Engine loading system
For the present investigations load banks have been fabricated. The load bank has been connected to alternator system. It comprises of six heating coils and nine filament lamp.
5.6.3) Engine control panel
For test purposes a set of engine control panel has been built, which is equipped with fuel supply system, measurement of various temperature indicators and output system for analyzing the emission characteristics and engine performance.
5.6.4) Fuel supply system
To measure the volumetric fuel consumption of the engine, a burette was placed on the control panel. By noting the time taken for 20 cc of fuel consumed by the engine, fuel flow was measured. A three way operated two position directional control valve and additional filter was added to modify the fuel system, which allows rapid switching between diesel fuel used as standard and the test fuels. Stopwatch and 20cc graduated burette was used to measure the volumetric flow rate.
5.6.5) Measurement of Power
On the control panel voltmeter and ammeter are also mounted. Ammeter is used to measure the current consumed by the load in the load bank where as voltmeter is used to measure the voltage in the load bank.
5.6.6) Measurement of temperature
To monitor the gas temperatures of the exhaust gas, lubricating oil, cylinder wall and the temperatures at the inlet and the outlet ducts, thermocouples were installed. By using these thermocouples temperature of these parameters will be measured by digital temperature indicators.
5.6.7) Measurement of speed and air flow rate
Infrared type digital tachometer was used to measure the speed of the engine. By pointing towards the sensor mark of the flywheel with the help of the laser beam of digital tachometer, speed was measured and it is indicated in the digital display of the tachometer.
5.6.8) Exhaust gas analyzer and smoke opacity
Exhaust gas analyzer was used to measure the opacity of exhaust gases.
Exhaust Gas
Measurement range
Resolution
NOx
0 - 4000 ppm
1 ppm
CO
0 - 10% vol. %
0.1 vl. %
CO2
0 - 20% vol. %
0.01 vol. %
HC
0 - 20000 ppm
1 ppm
O2
0 - 22% vol. %
0.01 vol. %
Table Exhaust gas analyzer specifications
Engine testing:
The performance and emission characteristics were evaluated by testing the engine fuelled with Diesel and diesel- ethanol blend to find out how each fuel will perform under sameengine and load conditions. The variables used in testing are given below:
Types of variables involved
Details of variables studied
Fuels used
Diesel and E10
Load (%)
0%, 20%, 40%, 60%, 80%, 100%
BSFC
At 0%, 20%, 40%, 60%, 80%, 100% load
BTE
At 0%, 20%, 40%, 60%, 80%, 100% load
Engine Exhaust emissions
CO, CO2, HC, NOx, Smoke( % opacity)
Table for engine testing on single cylinder diesel engine
Test conditions
Ethanol and ethanol- diesel blend were tested by keeping all the independent variables same.The experiments were carried out in a diesel engine fuelled with disel and diesel- ethanol blend (E10) under variable load conditions( 0% to 100%) in steps of 20%. With the help of this study, we compared the suitability of these two fuels for application of engine and the optimum fuel for implementation was determined.
The parameters such as engine speed, rate of fuel consumption, generator output, rate of airflow, exhaust gas temperature were measured so as to evaluate the performance parameters. The calculations were made for performance parameters with the varying load (0% to 100%) in steps of 20%.
The engine emissions like CO, HC, CO2, NOx and smoke were measured using exhaust gas analyzer and smoke meter respectively. The observations were recorded by exposing the sensor of analyzer to exhaust gases.
Engine Test Procedure:
The engine was made to start by setting the load bank switches closed. The fuel control lever was made to set towards higher fuel rate. First of all, the speed is set to 1000 rpm through fuel control lever.
The engine was made to run for about 30 minutes before the starting of the test so as to get stabilization and then in subsequent testing, the stabilization period of 10 minutes was allowed. First of all, the tests were carried out using pure diesel as fuel by varying the load from 0% to 100% and the speed of engine was kept constant.
By closing the load switch, the load was applied on engine. The load was made to increase by varying the current and voltage. The loading of engine was done continuously till the dense black smoke appeared from exhaust pipe. Further, loading cannot be done.
Under each operating condition, the load on control panel, the speed of the engine(rpm), time taken for 25ml of fuel consumption, manometer reading, exhaust gas temperature, cooling water temperature, ambient temperature and emissions were noted down.
For ethanol- diesel blend, the same procedure was followed.
The experiments were conducted for diesel and its blend and three replications were msade on each setting of independent variables.
The results of emission and performance characteristics obtained were compared with that of pure diesel.
4.4) PERFORMANCE PARAMETERS
4.4.1) BRAKE THERMAL EFFICIENCY
It is the ratio of energy in the brake power to the input fuel energy in appropriate limits.
ᶯbth=bp / (mass of fuel per sec Ã- calorific value of fuel)
4.4.2) BRAKE SPECIFIC FUEL CONSUMPTION
It is the weight of fuel burned per hour to produce a given amount of brake horse power in a reciprocating engine.
4.4.3) EXHAUST GAS TEMPERATURE
Exhaust gas is emitted as result of combustion of fuels. Exhaust pipe is used to discharge these gases into atmosphere. The temperature of exhaust gas is measured by exhaust gas temperature gauge.
Exhaust Gas Temperature represents the exact temperature of the fuel mixture after it is combusted in the cylinder. This should be measured as close to the outlet valves as possible.
4.5) EMISSIONS MEASUREMENT
The CI engine exhaust gases contain oxides of nitrogen (NOx), oxides of carbon(carbon monoxide (CO) & carbon dioxide(CO2)) and organic compounds which are unburned or partially burned hydrocarbons (HC). Specific hydrocarbon compounds in the exhaust gases are the source of diesel odor. Diesel engines are an important source of particulate emissions; between about 0.2 and 0.5 percent of the fuel mass is emitted as small (-0.1 m diameter) particles which consist primarily of soot with some additional absorbed hydrocarbon.
4.5.1) OXIDES OF NITROGEN
Exhaust gases of a CI engine can have up to 2000 ppm of oxides of nitrogen. Most of nitrogen oxide(NO),with a small amount of nitrogen dioxide(NO2).There are all grouped together NOx, with x representing suitable number. NOx is very undesirable. Regulations to reduce NOx emissions continue more and more stringent year by year. Released NOx reacts in the atmosphere to form ozone and is one of the major causes of photochemical smog.
4.5.2) CARBON MONOXIDE
The fuel air equivalence ratio is used to control carbon monoxide (CO) emissions from internal combustion engines. With the increase in equivalence ratio, CO concentration in the exhaust increases steadily for fuel-rich mixtures whereas for fuel- lean mixtures, CO concentrations in the exhaust change little with equivalence ratio.
4.5.3) UNBURNED HYDROCARBON
Hydrocarbon or more appropriately organic emission, are the consequences of incomplete combustion of the hydrocarbon fuel. Diesel fuel contains hydrocarbon compounds with higher boiling points, and hence higher molecular weights, than gasoline.Also, substantial pyrolysis of fuel compounds occurs within the fuel sprays during the diesel combustion process. Thus, the composition of the unburned and partially oxidized hydrocarbons in the diesel exhaust is much more complex than in the spark-ignition engine and extends over a larger molecular size range.
4.5.4) PARTICULATE EMISSIONS
Diesel particulates consist principally of combustion generated carbonaceous material (soot), on which some organic compounds have become absorbed. Most particulate material results from incomplete combustion of fuel hydrocarbons; some is contributed by the lubricating oil. The emission rates are typically 0.2 to 0.6 g/km for light-duty diesels in an automobile. In larger direct-injection engines, particulate emission rates are 0.5 to 1.5 g/kWh. The composition of the particulate material depends on conditions in the engine exhaust and particulate collection system.
4.5.5) SMOKE
It is a visible indicator of combustion process and results due to incomplete combustion. The instrument used for measuring smoke is smoke meter.
RESULTS AND DISCUSSIONS:
Test fuel characterization:
The important physico- chemical properties of diesel and its blend E10 were determined by standard methods and were compared.
Properties
Diesel
E10
Density( gm/ml)
0.832
0.823
Kinematic viscosity (centipoise)
2.56
2.12
Calorific Value(KJ/kg)
43228.9
42317.17
Surface Tension(mN/m)
31.88
26.5
Flash Point(â-¦C)
65.7
20
Fire Point(â-¦C)
73.8
23
Cloud Point
Pour Point(â-¦C)
-18
-2.4
Physico-chemical properties of diesel & Diesel- ethanol blend(E10)
Effect of load and blend on specific fuel consumption
The trends of SFC increased for the blend as compared to the diesel, when observations were evaluated between the specific fuel consumption and different loads. SFC is increasing with the increase in content of ethanol in diesel. This is due to the fact that ethanol has low calorific value as compared to diesel. Maximum SFC is obtained at 20% load at 16th cycle. Heat value of ethanol is about 2/3 of that of the diesel. There is remarkable increase in value of SFC at lower loads as compared to higher loads, as there is incomplete combustion due to the low ignition delay of ethanol diesel blend (E10).
Figure SFC during 1st cycle reading
Figure SFC during 8th cycle reading
Figure SFC during 16th cycle reading
Effect of load and blend on brake thermal efficiency
It can be seen from the graphs that the BTE is improved for all engine conditions when it is fuelled with ethanol-diesel blend as compare to diesel. During 8th cycle maximum value of BTE was found to be 39.1% as compare to 36% for diesel. BTE was improved for blends as boiling point of ethanol is lower than that of diesel, due to oxygenate of ethanol combustion is more complete in fuel rich zone so that the combustion efficiency is improved and also there was decrease in the heat losses inside the cylinder as flame temperature of ethanol is lower than that of diesel.
Figure BTE during 1st cycle reading
Figure BTE during 8th cycle reading
Figure BTE during 16th cycle reading
Effect of load and blend on exhaust gas temperature
It can be seen from the graphs that EGT increases with increase in engine loading for all the fuels tested. The temperature increases linearly from 132 °C at no load to 445 °C at full load conditions. This is due to the fact that when load increases more amount of fuel is required to generate extra power. With increase in the concentration of ethanol in diesel EGT are increased due to more heat losses and lower BTE of blends.
Figure EGT during 1st cycle reading
Figure EGT during 8th cycle reading
Figure EGT during 16th cycle reading
Emission Study
Effect of load and blend on NOx Emissions
When observations were evaluated for NOx values as parts per million (ppm) for different fuel blends and at different loads, it was observed that NOx were decreasing for increasing proportion of ethanol in the blend. It was due to the increased exhaust gas temperatures. The variation of NOx emissions is linear to the load of the engine. When load increases, the fuel-air ratio also increases which results in the increase in combustion chamber gas temperature. This in turn increases the NOx formation that is responsive to increase in temperature.
Figure NOx emissions during 1st cycle reading
Figure NOx emissions during 8th cycle reading
Figure NOx emissions during 8th cycle reading
Effect of load and blend on CO Emissions
The graphs below shows that CO emissions decreased for blends due to complete oxidation as compared to diesel. The CO produced during combustion of blends might have been converted into CO2 by taking the extra oxygen molecules present in the blends thus reducing formation of CO. Initially at no loads CO decreased but increases sharply at medium and full load conditions. This is due to the fact that at low loads cylinder temperatures might be too low which increases with the loading as more fuel is injected at higher loads. Performance of the engine was improved due to relatively better burning of the fuel at elevated temperature which results in decreased CO. However on further loading, the excess fuel required lead to the formation of more smoke, which prevents oxidation of CO into CO2 that results in sharp increase in CO emissions.
Figure CO emissions during 1st cycle reading
Figure CO emissions during 8th cycle reading
Figure CO emissions during 16th cycle reading
Effect of load and blend on CO2 Emissions
CO2 emissions increases gradually with the load on the engine and reaches a maximum value of 9% for E10 blend. As more fuel was converted from CO to CO2, it indicates better combustion. At constant engine speed higher oxidation of fuel is due to the higher content of CO2 emissions. For power conversion more heat is released. Graphs below shows that CO2 emissions are increased with load.
Figure CO2 emissions during 1st cycle reading
Figure CO2 emissions during 8th cycle reading
Figure CO2 emissions during 16th cycle reading
Effect of load and blend on smoke emissions
There was a slight increase in smoke for E10 blend in comparison to diesel fuels. This was due to the incomplete combustion of fuel and high viscosity as compared to diesel. Up to 80 % of the load in case of diesel smoke opacity was less. As compare to lower loads smoke increases more at higher loads. This is due to at higher loads more fuel is used and air-fuel mixture is prepared in a short time which leads to the reduction of combustion quality for blends when compared to diesel. Smoke emissions when taken into consideration diesel are the optimum fuel and it can reduce further through optimized injection timing.
Figure CO2 emissions during 1st cycle reading
Figure CO2 emissions during 8th cycle reading
Figure CO2 emissions during 16th cycle reading
Effect of load and blend on HC Emissions
It is seen that increasing load per cent has an adverse effect in increasing HC emissions. The increase in HC is primarily due to the incomplete combustion of ethanol blend within the combustion period. Because of the non homogeneity of fuel-air mixture some local spots will be too lean to combust properly and others may be too rich will not have enough oxygen to burn all the fuel.
Figure CO2 emissions during 1st cycle reading
Figure CO2 emissions during 8th cycle reading
Figure CO2 emissions during 16th cycle reading
CONCLUSIONS
The main aim of this project is to study and compare the effect of physicochemical properties, performance parameters, emission characteristics of diesel and ethanol-diesel blend (E10). Based on the results of this study, the following conclusions are drawn:
FUEL PROPERTIES
Ethanol has lower density value as compared to diesel on mass basis. Ethanol-diesel blend lowers the volumetric energy density of the fuel in proportion to the content of ethanol.
Ethanol has low fuel viscosity as compare to diesel. The viscosity does not reach the minimum requirements for diesel fuels with ethanol content of 10-20 %.
The values of calorific value, flash point, fire point, pour point, cloud point and surface tension are found to be lower for ethanol as compare to diesel.
PERFORMANCE PARAMETERS
Ethanol-diesel blend has improved SFC, BTE and EGT. All three factors are increasing with increase in content of ethanol in diesel as compare to diesel fuel.
EMISSION CHARACTERSTICS
NOx emissions have been improved as content of ethanol increased in diesel fuel when compared with diesel fuels.
CO emissions decreased at low loads but increased sharply at medium and full loads.
Smoke opacity is increasing with the ethanol content in diesel fuel. At high loads smoke emissions increases more rapidly as compare to low loads.
HC emissions increased at various loads along with the content of ethanol in the blend fuel.
The overall emission characteristics has been found best for the case engine fuelled with diesel.
5. TIME PLAN
Sr. no
Activities
November
December
January
February
March
April
1
Decided the objective of project
2
Learning the basic knowledge of the project
3
Lab Testing
4
Analysis of performance and emission characteristics of the engine
5
Finalization of Results
6
Conclusion
